<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script>
        var aList = ['a', 'b', 'c'];
        aList.map(function (item, i) {
            // 第一个参数是成员值
            // 第二个参数是成员索引值
            alert(item + ' | ' + i);
        })

        // concat会返回一个新数组
        var aList2 = aList.concat('d', 'f');
        var aList3 = [1, 2];

        var aList4 = aList.concat(aList3)
        console.log(aList2);
        console.log(aList4);
    </script>
</head>
<body>
    
</body>
</html>